ALEXA XT/XR Frequently Asked Questions

Welcome to the frequently asked questions about ALEXA XT cameras (XT) and ALEXA Classic cameras with the XR Module upgrade (XR). This FAQ pertains to cameras with 'Software Update Packet 10 (ALEXA XT/XR)'. Directions given are always from the operator's point of view. This FAQ supersedes any earlier versions. To avoid redundancy, information contained in the ALEXA web pages or manuals will not be duplicated here. More FAQs can be found here:

1. XR MODULE

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Can I switch a classic ALEXA back from the XR Module to the SxS Module?

First, the upgrade can only be performed by ARRI service stations, since there are a complex board exchange and some complex firmware update procedures involved. Theoretically, after an ALEXA Classic has been upgrade with the XR Module, ARRI service could switch the camera back to the SxS Module. However, there really is no reason, since the only features not available in the XR Module are dual recording (same material onto both cards), which is a rarely used feature, and ARRIRAW T-link, which is not necessary anymore once you have an XR Module. Plus there is labor cost each time.

Will my sensor be 4:3 after I install the XR Module upgrade?

ALEXA Classic cameras that receive the XR Module upgrade will retain their sensor aspect ratio. So if you take, for instance, an ALEXA Classic, which has a 16:9 sensor, and you had ARRI service upgrade this camera with the XR Module, the camera would still have a 16:9 sensor.

Will my camera have more licenses after I install the XR Module upgrade?

No. Classic ALEXA cameras that receive the XR Module upgrade will retain their installed licenses. No new licenses will be added as part of the XR Module upgrade. So if you take, for instance, an ALEXA Classic with no High Speed license installed, and you had ARRI service upgrade this camera with the XR Module, the camera would still have a no High Speed license.

2. GENERAL

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Can I upgrade an ALEXA Classic all the way to the full ALEXA XT feature set?

No. While you can get a lot of the ALEXA XT features as individual upgrades for ALEXA Classic cameras, ARRIRAW Open Gate is only possible with the sensors inside ALEXA XT cameras, the LDS PL mount is not available as an individual upgrade, there are a number of changes we made to the ALEXA XT electronics for future features and, last but not least, a full ALEXA XT upgrade option would be unfair towards all those who buy new ALEXA XT cameras.

Can I attach an SxS Module to an ALEXA XT camera?

No. The ALEXA XT is a new camera with some new electronics inside that do not support the SxS Module. This is no problem, however, since the ALEXA XT has a new left side (the XR Module) that can accept either XR Capture Drives for recording ARRIRAW or ProRes/DNxHD, or an SxS Adapter that can accept SxS PRO or SxS PRO+ cards for recording ProRes or DNxHD.

Are there features the ALEXA Classic cameras have that the ALEXA XTs don't have?

The only features that ALEXA Classic cameras have that ALEXA XT cameras do not have are:

ARRIRAW T-link output on the REC OUT BNC connectors. This is not needed anymore on ALEXA XT cameras (or ALEXA Classic cameras with the XR Module upgrade) since they can record ARRIRAW in-camera and at faster fps rates.

Dual recording; this is recording the same data to two SxS PRO cards at the same time. This has been used very seldom by our customers.

Frame grabs of ARRIRAW images in-camera are not possible with ALEXA XT or ALEXA Classic cameras that have the XR Module upgrade installed. However, most software that is used to debayer the ARRIRAW images can easily create frame grabs.

3. 4:3 SENSOR MODE

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What is the advantage of a 4:3 sensor?

The ALEXA 4:3 sensor is much taller than those in all other digital cameras, and this has great advantages for shooting with anamorphic lenses as well as for shooting with spherical lenses.

When shooting with anamorphic lenses, the tall 4:3 sensor area used on the ALEXA sensor is almost the same physical size as the area used on 35 mm film for shooting anamorphic. As a result, the angle of view of anamorphic lenses is the same on ALEXA as it used to be on film cameras. Anyone who has shot anamorphic films will be immediately familiar with shooting anamorphic on ALEXA. In addition, the area used is much larger than if you cut it out of a 16:9 sensor, and this means that ALEXA can collect more light, which means less noise and a better image.

But even when shooting with spherical lenses there is a great advantage to 4:3 because it gives you extra room on top and below your main image. This is great for placing VFX tracking markers in the top and bottom of the image. It is also great to fix a number of common problems in post: a microphone in the top of the image, a dolly track in the bottom or a shot where an actor sat up/down too fast and the camera tilted up/down too late.

In the graphic below you can see on the left side the film/sensor area used by film cameras (orange) and ALEXAs (blue), which are almost identical. The 1.95:1 area is the area used by an anamorphic lenses. 2.39:1 is the anamorphic projection aspect ratio, and the lens squeezes the image by a factor of two, so 2.39 divided by 2 = 1.195. On the right side you can see the significantly smaller area used for anamorphic lenses by a camera with a 16:9 sensor.

So why not shoot everything in 4:3 sensor mode?

While 4:3 sensor mode is a necessity for shooting with anamorphic lenses and a great help for VFX when shooting with spherical lenses, the format does contain more data. Thus the maximum frame rate in 4:3 mode is lower than in 16:9 and recorded files will be larger in 4:3. In addition, having two entirely independent HD-SDI outputs (REC OUT and MON OUT) is only possible in 16:9 regular speed (even though the SUP 10 feature 'REC OUT = Clean MON OUT' helps in many recording formats), and 16:9 also has the largest surround view area.

Why can ALEXA record ARRIRAW at 96 fps but ProRes 4444 only at 48 fps?

ProRes is a compressed data format, while ARRIRAW is uncompressed. Compression, especially at the high quality that ProRes exhibits, takes lots of processing power, and so ProRes 4:3 is limited to 48 fps.

4. OPEN GATE SENSOR MODE

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What is Open Gate?

Only ALEXA XT cameras are capable of Open Gate mode. Since SUP 9.0, ALEXA XT, XT Plus and XT Studio are capable of Open Gate sensor mode. In SUP 10, Open Gate mode for ALEXA XT M cameras was added.

In Open Gate sensor mode the whole area of the sensor (3414 x 2198 photo cells) is captured. This is great for capturing for a 4K release or for gaining more resolution for repositioning, resizing, rotating or stabilizing in post. Open Gate is only available in ARRIRAW. Surround view is not available in Open Gate mode, as we are already using all photo sites for the recorded image. The image will be displayed in the electronic viewfinder and on the MON OUT output in pillar box format.

Which lenses can I use with Open Gate?

The larger sensor area requires lenses that cover an image circle of 33.5 mm. You should, of course, always test your lenses before using Open Gate mode. Our initial tests have shown Open Gate mode to be compatible with:

most spherical primes longer than 20 mm

spherical zooms at the longer end of their range

the Alura Lightweight Zoom 15.5 - 45/T2.8 from 17 mm to 45 mm

the ARRI Ultra Wide Zoom UWZ 9.5 - 18 at all focal lengths. It is perfect for all Open Gate wide angle work.

How can I create custom frame lines for Open Gate?

From version AFLC-3 on, the online ARRI Frame Line Composer supports frame lines for all sensor modes, including Open Gate.

Can I use the ALEXA Studio/XT Studio Optical Viewfinder with Open Gate?

Yes, but note that the optical viewfinder of the ALEXA Studio and ALEXA XT Studio cannot show the entire width of the Open Gate image. We recommend to use MON OUT as a reference or use the EVF-1 for exact framing.

Can I record audio with Open Gate?

No. Since we need all the processing power available to process the Open gate image data, audio recording in Open Gate sensor mode is not possible.

5. XR MODULE/XR CAPTURE DRIVE

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What is the data rate of the XR Capture Drives?

The XR Capture Drives (identified by the golden ring) have a tested data rate of over 860 Megabytes per second. That is 6,880 Megabit per second or 6.7 Gigabit per second! We believe these to be the fastest drives on the market, and this is what makes uncompressed ARRIRAW at 120 fps possible.

How can I format the XR Capture Drives?

The XR Capture Drives can be formatted in the camera or through the Capture Drive Docks.

What is the file format of the XR Capture Drives?

Depending on the recording mode of the XR Module – ARRIRAW or ProRes/DNxHD – an XR Capture Drive is formatted with one of two file systems:

When the camera is set to uncompressed ARRIRAW recording, the XR Capture Drive is initialized as a Codex volume, which offers 455 GB of storage space. This allows for 47 minutes of 16:9 ARRIRAW recording at 24 fps or 9 minutes of 16:9 ARRIRAW at 120 fps. This also allows the use of the Codex Virtual File System (VFS).

When the camera is set to ProRes 2K, ProRes HD or DNxHD recording, the XR Capture Drive is initialized as a UDF volume, which offers 229 GB of storage space (the reason for the reduced storage space is that currently only one SSD inside the XR Capture Drive is utilized for recording in this mode). This equals over 100 minutes of ProRes 4444 in 16:9/2K or three hours of ProRes 422 HQ at 24 fps. Using the UDF file system on XR Capture Drives as well as on SxS PRO cards maintains compatibility to the established ALEXA ProRes/DNxHD workflows. Thus, little to no time will be required to adapt existing workflows to the XR Capture Drives. As with SxS PRO cards, an XR Capture Drive containing ProRes 2K, ProRes HD or DNxHD clips can be accessed directly, without the need for (but also without the benefits of) the VFS. The file names and directory structure created on the drives or cards are the same for the SxS Module and the XR Module.

What is the Codex Virtual File System (VFS)?

When a Capture Drive with ARRIRAW footage is loaded on a computer, it shows up like a regular external drive. Operating underneath, however, is the Codex Virtual File System (VFS). The VFS can present, for example, readily processed DPX files, MXF/DNxHD and/or QuickTime/ProRes proxies next to the original ARI files on the Codex volume. Except for the recorded data on the drive, none of these additional files actually exist. It's only when these files are requested, that they are generated, on-demand, and on the fly. Hence the term "virtual". The file formats, file naming and directory structure that will be presented by the VFS are fully configurable through the Codex Platform software. This makes the VFS a highly flexible tool for providing exactly the material you require, when you want it, without redundant processing and storage overhead on your drives.

Please note that, in order to reduce the purchase price, the Capture Drive Dock (USB-3 no VFS license) does not come with the full VFS features, but those can be added with a license from Codex. The Capture Drive Dock (USB-3), the Capture Drive Dock (Thunderbolt), Capture Drive Dock (SAS) and the Vault have full VFS capabilities included.

Can I use the Onboard S (OBS) Capture Drives (CDX-7720) in the XR Module?

ARRI has not validated the OBS Capture Drives for use in ALEXA XT cameras or ALEXA Classic cameras with an XR Module upgrade but the OBS Capture Drives have been tested by Codex. Please note that OBS Capture Drives will not support the high speeds (like ARRIRAW at 120 fps, for instance) that the XR Capture Drives are capable off.

Can I use the SxS Adapter in the Capture Drive Docks or Vault?

No. The SxS Adapter is designed to work only in the camera. Making it compatible with the docks would have made it more expensive, and there are other, more affordable SxS download solutions available. Also, the Vault can accept SxS cards.

Is the ALEXA bigger because of the XR Module?

The XR Module makes the ALEXA camera only 8 mm wider. In the image below the camera on the left has an XR Module installed, and the camera on the right an SxS Module.

How much more power does the XR Module need?

An ALEXA with an XR Module installed will use about 6W more power when running at 24 fps in comparison to the same camera with the SxS Module.

What happens when I open the XR Module door and then remove the XR Capture Drive while recording?

When you open the XR Module door while recording, nothing happens; the camera will continue to record. Just as with ProRes on SxS PRO cards, we have made sure that the recorded file will not get corrupted when the drive it removed during recording. The last 5 seconds of footage may not be recorded, however.

What happens when I accidentally rip off the XR Module door?

Don't laugh. Since we know how it is on a set, we have tried to consider every possibility. When the door mechanism malfunctions or you inadvertently destroy the XR Module door (let's say you dolly backwards through a door when the XR Module door is open), you can still continue to record. In order to mount an XR Capture Drive, push it into the XR Module and then push and hold the drive's round button for 3 seconds. This will mount the drive, an action that would normally have been triggered by closing the door. To un-mount the drive, push the round button on the drive again (a short button push will suffice).

6. INTERNAL FILTER MODULE IFM-1

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What are the components of the Internal Filter Module?

Do the ALEXA XT cameras come with FSND filters?

No. The ALEXA XT cameras (except the ALEXA XT Studio) come with the Internal Filter Module (IFM) filter holder pre-installed, but without the necessary shim and the Full Spectrum Neutral Density (FSND) filters. The filters have to be purchased separately. They are available individually or in a basic or full set. The sets also include the shim. If you are purchasing the filters individually, you also have to purchase one shim.

Can I use the IFM-1 in all ALEXA cameras?

All except the ALEXA Studio and ALEXA XT Studio. They have their own, motorized ND filter system that makes them incompatible with the IFM-1 system.

Can you install the FSND filter in the ALEXA Studio motorized ND filter slider?

No. The ALEXA Studio and ALEXA XT Studio need special ND filters that are very thin, so using or installing FSND filters is not possible.

Do the FSND filters present a dirt problem?

No, on the contrary. Lenses get changed much more often than ND filters. As soon as a FSND filter is installed in the camera, it protects the sensor during each lens change. The FSND filters are also relatively far away from the sensor, so if there are small specs of dirt on the filter, they will not show up in the image at most common T-stops.

Will the FSND filters also be available in other sizes as external filters?

No. This is currently not planned since the trend seems to be for ND filters to be included inside cameras.

Are the filters between the ARRI IFM-1 and the Clairmont system compatible?

No. The Clairmont system has the magnets in the filter holder in the lens mount, and the ARRI system has the magnets in each filter frame.

Are other filter types available for the IFM-1?

No. Currently there are only the eight FSND filters and one optical clear available.

Why are the FSND filters not motorized?

We actually tried this, and the resulting mechanism looked like a big old wart on the front of the ALEXA camera, would have made the camera significantly bigger, heavier and more expensive. We showed the drawings to some rental houses and they all agreed that it would not be worth the extra weight, size and price.

Why can I not slide the new filters into the side of ALEXA?

We looked at a sliding mechanism, but there were some mechanical problems and this would have created a serious dirt contamination issue. Not only would the slot be an open invitation for all kinds of debris to come into the camera and settle on the sensor, but the filter would also be very close to the sensor, and that makes any dirt on the filter very visible.

7. LDS PL MOUNT ON ALL ALEXA XT CAMERAS

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What is the ARRI Lens Data System (LDS)?

The ARRI Lens Data System (LDS) collects lens information, distributes this information immediately and the ALEXA can record it as metadata.

Lens information can be collected in three ways: first, an ARRI LDS lens will send lens info and the position of the lens rings automatically to the camera or UMC-3A. There are 41 different ARRI lenses that have LDS encoders built-in, including the Master Anamorphics, Master Primes, Master Macro 100, LDS Ultra Primes, Master Zoom 16.5 – 110 and Alura Lightweight Zooms. Second, we are working on ALEXA support for the Cooke /i lens data system, which should be available sometimes in 2013. And third, as long as an ARRI lens motor is attached to the lens, you can call up the lens' profile in the camera and get all the LDS functions, including metadata. This third option is called the Lens Data Archive (LDA).

Once the lens information is collected, the camera (or UMC-3A) will make this information immediately available to ARRI cameras and accessories. Thus the ALEXA can display lens info on its display and insert numerical lens information into the electronic viewfinder or MON OUT video output. Thus the WCU-3 can display lens info as numbers, and the WCU-4 and LDD-FP can show an easy to use graphical display that mimics the lens rings.

But the ALEXA does even more: it outputs the information as a real-time data stream on HD-SDI (both as raw encoder values and as interpreted data). This has already been used by Transvideo on-board monitors, which can display the lens data, and Lightcraft, who use this real-time lens info for virtual set work.

Additionally, all that lens metadata gets recorded by ALEXA in ARRIRAW, ProRes and DNxHD at all frame rates.

What are the advantages of the ARRI Lens Data System (LDS)?

There are two big benefits to LDS: on the set and in post.

On the set the ARRI Lens Data System allows faster and smoother working, since everyone can see what lens is up and what the settings on the lens are. Focus pulling is easier for the camera assistant by looking at the LDS display of the WCU-4, and by using some help like a graphical display of the available depth of field, info on hyperfocal distance and focus markers, which can not only be set easily but will vibrate when hit, so the assistant does not even have to look at the screen to know the focus mark is reached. Recording the LDS data burn-in from the MON OUT signal helps with continuity.

In post, this data can be extracted using our MetaExtract software for ProRes or the ARRIRAW Converter software for ARRIRAW. Having this data makes compositing a lot faster. We had recently a number of US car commercials that have used this feature to speed up the post process. A number of visual effects heavy feature films and TV series have also used the LDS data.

Which lenses support the Lens Data System?

There are 41 models of lenses from ARRI that support the Lens Data System (LDS).

ARR/Zeiss Master Anamorphics

ARRI/Zeiss Master Primes

ARRI/Zeiss Master Macro 100

ARRI/Zeiss LDS Ultra Primes

ARRI/Zeiss Master Zoom 16.5 - 110

ARRI/Fujinon Alura Lightweight Zooms

In addition, ALEXA XT cameras also support the Cooke/i protocol. None-LDS lenses can be accommodated by storing the lens profile in the camera and using an ARRI lens motor. This is called the "Lens Data Archive" and provides all the features of the LDS.

8. VIEWFINDER MOUNTING BRACKET VMB-3

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Can I use the VMB-3 on all ALEXAs?

Yes, the VMB-3 is backwards compatible with the ALEXA Classic cameras.

Why does my Viewfinder Mounting Bracket VMB-3 only have one end-cap?

The end cap of the VMB-3 is designed to prevent the sled from falling off the two 15 mm rods when pushed too far forward. For that only one end-cap is needed, so the VMB-3 is equipped with only one.

Is the Viewfinder Extension Bracket VEB-3 compatible with VMB-1, VMB-2 and VMB-3?

Yes, the VEB-3 can be used on all generations of viewfinder mounting brackets. However, the safety catch feature, that prevents the VEB from sliding out of the VMB, only works when using a VEB-3 with a VMB-3.

9. SUPER SILENT ALEXA XT FAN

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Was there a sound problem with the original ALEXA fan?

No, but we found a new, even more silent fan and thought that a camera can never be silent enough. Just ask your sound person.

How can I tell if my ALEXA Classic has been updated with the new fan?

The new fan has an orange dot in the center of the foam distance pad. When you see the orange dot, you have the new super silent fan.